symmetal

The spacing of 66.2mm from the flat rear end of the flattener to the image plane is when the adjustable section is set to zero. For a DSLR with a standard 55mm spacing between the front of the T adapter and the image plane you would unscrew the adjustable piece shown below until the left edge is at 11.2mm on the scale. So the overall FF spacing is then 55 + 11.2 = 66.2mm, the correct distance. You then use the locking ring (below the blue arrow) to lock the adjustable section. You have 15mm of adjustment so if you don't use a DSLR you get the physical distance between the rear flat of the FF and the image sensor anywhere between 51.2 and 66.2mm with standard spacers and you can make up the difference with the adjustment. As Annehouw says using filters requires the 66.2mm to be increased by 1/3 the thickness of the filter. Also the sensor protect window on astro cameras needs to be counted as a filter as well so add 1/3 the thickness of that too. If you have a 2" filter fitted in the rear of the flattner this stops the adjustable section reaching zero and it can only be adjusted between around 7mm to 15mm. Alan

The Hitecastro controller looks to be a generic controller and isn't tailored to specific motors. Stepping motors are intended to work with an optimum current to give the best turning torque without overheating. The controller should vary the voltage applied to the motor to maintain that current. When turning the motor generates back EMF which opposes the force trying to turn it so the voltage applied to the motor is increased to counteract this. Some controllers will also reduce the current through the motor when it detects the motor isn't turning, either by no step pulses applied or no back emf generated, to maintain the holding torque without overheating the motor. If you aren't using microstepping then the holding torque is not usually necessary to keep the motor stationary and the detent torque (resistance to turning when no power is applied) is sufficient to hold the focuser in place. The lakeside controller doesn't use microstepping as the gearing down is sufficient to give good stepper resolution, so doesn't use continuous power mode and relies on detent torque to hold it in place which is sufficient. If your driver doesn't have the option so set the current through the motor than some motors will run hotter than others dependant on the motor winding resistance. In your situation I would disable the continuous mode operation in the driver and things should stay nice and cold. It's likely that it doesn't reduce the current in continuous mode operation when the motor is stationary. Difference between detent torque and holding torque Alan

There is possibly an option in the driver to power the motor continuously or only when you want to move it. As the lakeside focusers are well geared down it's normal to only power them when they move. If you use microstepping on the motor then continuous power is needed but the normal detent torque when unpowered is sufficient to stop them slipping. If continuous power is applied they will get warm or quite hot if the driving current is high. Alan

If your camera hasn't been opened then hopefully any dust is just on the front of the protect window so cleaning that should suffice. The 1600 doesn't have a heated protect window, (at least the early ones didn't) so there is a chance of condensation forming on the exposed front of the protect glass, though I admit have never had any issues with this and I cool my 1600 down to -30C in the winter. You can buy heater strips from Zwo to fit around the protect window if you want. Short exposures (around less than a second) on CMOS cameras operate in a different mode to long exposures as discussed here and in more detail here. In order for the flats to match the lights you should take longer flat exposures of around 2 seconds or more, and corresponing darks (called flat darks), matching the length of the flat exposure to calibrate the flats and not just use bias instead. You can use bias if you wish with short exposure flats and some people report no issues but it seems to be recommended not to use bias with CMOS cameras. It's fine to use bias with CCD cameras though. Alan

Graham, Generally the first sign of excessive moisture is ice forming on the sensor when you cool it below zero. This may not show up too much on the lights with just a slight patterning visible on the sky background but flats show it very well. At least that's how it was with my 071 camera. My 1600 is first generation and I've had no moisture or icing issues with it at all and it has never been opened or had the desiccant tube fitted. Only new flats are needed after cleaning. Bias is not normally used with CMOS cameras as darks and flat darks are preferred. Alan

The manual originally stated to leave the tube screwed in the side for 24 hours and then remove and replace the screw but posts on CN and elsewhere recommend leaving the tube in place permanently once you first use it as the 24 hour cycle has little effect. There are 4 desiccant tablets inside the camera surrounding the sensor so if they are 'saturated' then plugging 2 tablets in the side won't have a great deal of effect as all they can do is absorb some moisture until all six tablets have the same water content. It would take longer than 24 hours for this to happen I would think as the hole in the tube is quite small and so the moisture exchange would be slow. You could keep repeating this procedure drying the two tube tablets in the microwave or oven each time but this would take quite a time. As you seem to have dust bunnies present it's worth removing the camera front plate as described in the post above and drying out the 4 internal tablets in the microwave or oven. You can then clean the sensor and protective glass plate and reassemble with the newly dried out tablets. If you wish, you could at this point keep the tube attached to the side with 2 more tablets and every month or so dry these 2 tube tablets out and replace. This should stop the internal tablets getting too saturated to the point where they stop working. It depends on how well sealed the camera sensor chamber is. Some cameras go for years without problems while others have moisture problems every few months. Later cameras like the ASI071 still have the screw hole in the side but don't include the desiccant tube anymore and you can't buy it separately so I think they realised it has little benefit. Alan

vlaiv has pretty much covered it, but I'll add a few extras. The telescope itself has no software for recording or processing images. With a DSLR you can record a video standalone but it's much easier using capture software like APT which runs on your Windows computer. The camera takes the place of the eyepiece and is generally not used with an eyepiece as well so the telescope is in effect just a long focal length camera lens. Astro cameras come with an adapter to enable them to be fitted to the scope just like an eyepiece would be. DSLRs require an appropriate T2 adapter to attach themselves to the scope. As vlaiv said a dedicated astro camera can be a lot easier to work with as there are more software options for image capture like Firecapture or Sharpcap which are free or cost very little for some extra features. I believe there is an Ascom driver written for Canon DSLRs which does enable them to work with Sharpcap. Ascom is a 'standard' interface to allow Astro programs and hardware to communicate with each other. Astro cameras also enable recording in an uncompressed video format which is much better for stacking to get better quality images, than using compressed video formats like you get with DSLRs (.mov or .mp4) The compression artefacts negate some of the benefits of stacking. Also many DSLR video formats downsample the sensor image size to match the common video size formats and aspect ratios which loses more resolution. A few DSLRs do allow centre cropped video recording where only the centre of the sensor which pixel matches the video format is used. This enables a sharper recording than the downsampled full frame version. Most Canons can be adapted to use cropped video recording if the Magic Lantern firmware is installed in the camera alongside the Canon firnware. DSLRs only allow video recording in standard video framerates of 25 or 30fps (maybe higher in newer models, not sure). Astro cameras allow you to select a Region Of Interest (ROI) to record rather than the full frame (very useful for planets as they generally only cover a relatively small portion of the sensor). This enables much higher framerates up to 200fps or so to be used so you can record thousands of frames in 30 seconds or so. Stacking selects the best frames of the video to stack to give the sharpest image but the main benefit of stacking is greatly improving the signal to noise of the final stacked image allowing quite heavy sharpening effects to be applied without bringing up the noise too much. Autostakkert is a free commonly used video stacking program and Imppg (also free) gives good deconvolution sharpening routines. Photoshop etc. can be used instead or as well. Hope this helps. And I don't know what 'aci' is either 😀 Alan

I think that's confusing WilliamAstro. Normally, on a mono camera L is recorded using an IR and UV cut filter which his camera already has. Being a OSC camera he is effectively recording the luminance wavelengths split into RG and B by the camera bayer matrix. An IR pass filter records only IR wavelengths and can be used as a substitute for luminance for mono planerary imaging as it is less affected by seeing. The built-in UV-IR cut filter on his OSC cameras doesn't allow IR only recording. Alan

The UV/IR cut sensor window is the same as a Luminance Filter so you don't need an extra luminance filter. It will block UV and IR wavelengths which is what you need to record one-shot RGB images on your colour camera. Alan

Yes, nothing worse than going to bed with a nagging problem on your mind.😀 At least your cable colours were correct. I wired up a USB cable I'd cut short and after it didn't work found that although the cable had the right colours they hadn't bothered wiring them to the correct pins on the moulded plug. Alan

Gina, I think your data & power connections are swapped over. On the USB3 connector datasheet the pcb footprint is shown from the component side. As you're viewing from the PCB side you need to swap the red and white wires over and as well as the black and green wires. Alan

Have you told the stacking software to debayer during stacking. I had a similar patterning effect when I stacked my first OSC image using Astroart and didn't tick the debayering operation on the stacking options. Debayering after stacking produced this patterning. Alan

Photoshop 6 released in 2000, and Photoshop 7 released in 2002 are the oldest of those listed. Photoshop CS (version 8 ) was released in 2003 and CS6 (version 13) was the last of the stand alone versions released in 2012, before the CC (version 14) subscription model version was released in 2013. The current version is still called CC though it is frequently updated and is currently on version 21. As MickJ has pointed out Astronomy Tools is only 8-bit in Photoshop 6 or 7. You're using the latest CC version of Photoshop so use the first Astronomy Tools version in your list. Here's the full Photoshop release history. Alan

Yes that's normal if it's set to automatically restore calibration as you mentioned earlier. PHD2 pulse guiding knows the Declination you're guiding at so automatically scales the RA movements according to the declination you were at when you calibrated. It also knows when to reverse guiding directions after a meridian flip. Using the ST4 cable, it's more basic and doesn't do this so you have to calibrate every time you change to a target at a different declination or the other side of the meridian. Alan

It depends on your guide camera/scope combination. I think PHD2 says a SNR over 10 or so is Ok but I never find stars with a SNR that low. Even very faint stars which are not good to guide on give me an SNR of around 50. If the star profile is stable and doesn't jump around too much from one exposure to the next then whatever SNR figure you get with an exposure around 2 secs should be fine. If you have your guide scope gain up very high in order to see the stars the SNR figures will be lower. Try reducing your guide scope gain if possible until at least one star in your FOV has a good profile and higher SNR. Alan

It's in the right position but is too bright and will saturate the guide camera. You want a fainter star that has a nice peak in its profile and not a flat top like Regulus would have. You want to keep the guide exposures around 2 seconds when calibrating to average out the seeing distortions. A star SNR around 100 or so is fine. Alan

Glad you got it working. . If your guide scope system isn't disturbed between sessions then yes, you can restore the calibration OK. If the guide scope ends up getting rotated a little when setting up your gear, then you need to do a calibration at the start of each session. Changing targets during a session is fine and no recalibration is needed as PHD2 is aware of the declination of the scope and can scale the RA guiding movements accordingly. ALan Edit. Yes, it's best to wait until it's darker and you get a good star SNR for calibration though it doesn't need to be full astro dark.

In the screenshot, looking South the Celestial Equator, 0 Dec, is the ligher blue horizontal line running through the word Sextans. Any star between DEC 0 and say DEC 20 degrees is fine for calibration but the closer to DEC 0 the more accurate it is. Ensure Stellarium is displaying EQ coordinates and not Alt/Az. Alan

Ideally you should point to a star on the Celestial Equator to calibrate. Look at Stellarium and display the celestial equator. Due to the Earth's tilt the Celestial Equator is at its highest when pointing South (from the Northern Hemisphere.) Currently the Celestial Equator is at altitude 38 degrees when pointing South. I think you're confusing RA/DEC and Alt/Az coordinates. RA/DEC are what is important to PHD2 calibration. Alan

No, that is the worst place to attempt to calibrate PHD as the RA movement is miniscule, and at the celestial pole the RA movement is zero. Also never 'sync' the scope looking at or near polaris for the same reason. Alan

Aim towards the South where Declination 0 is higher in the sky and so is easier to track for calibration as there is less atmospheric turbulance. Alan

It's the Declination of the target that matters rather than the altitude. The Iris Nebula is at Declination 68 degrees which is too high to calibrate on with any accuracy. Alan

From the error message I assume you were pointing to a target with a high declination. The higher the declination the less the scope has to move for a given distance in RA. So when the calibration routine did its step movements in RA, the distance the star actually moved was insufficient to get an accurate calibration reading. Hence the message that the star didn't move enough and it aborted calibration. At DEC 0 the RA moves the greatest distance for a given calibration step so is easier to accurately measure it. Hence the message to calibrate at less than DEC 20 degrees for best results. Alan

You're probably thinking of Verowire Gina. Alan

That's much better. Did you use dither at all as there is some vertical fixed pattern noise evident in the background. Alan